Where
Does A
SMOLT
Come From?
Materials: • Salmon Life Cycle poster • Copies of “Handout 7.1: Salmon
Smolts” for each student • Writing supplies Time required: Two to three lessons Level of conceptual difficulty: Simple Suggestions for assessment: Monitor the students’ discussion of the
life cycle poster to ensure that they
know that a smolt grows from a fry and
travels to an estuary. 78 SALMONIDS IN THE CLASSROOM: PRIMARY RESEARCH/DISCUSSION <
Have the class look at the Salmon Life Cycle poster, drawing
their attention to the part about the smolt. Ask students
to explain what the poster shows about where smolts come
from. They are fry which are old enough to leave their home stream. <
Have students use the poster to explain where a smolt goes. It swims downstream to the ocean and spends time in an
estuary. <
Have students discuss the difference between fresh water
and salt water, and use the poster to compare conditions in
a stream with those in an estuary. Water in an estuary is saltier. There are more plants and more to eat in an estuary, but
more predators, also. SUMMATION • Read “Handout 7.1: Salmon Smolts” or have students use it
to research the stage. Have students, in groups, write three
important things about a smolt. Salt
Water and
INTRODUCTION • Fresh
Water
This experiment demonstrates that salt
water makes cucumber slices wilt. It
leads to a discussion of how salmon must
adapt to salt water when they migrate to
the ocean. To leave time for the cucumber to soak,
you may wish to begin the experiment
the night before and have students
observe the change the following day. Materials: For each group of students: • Two containers with approximately
250 ml of water in each • Approximately 15 ml of salt • Two fresh slices of cucumber • Copies of “Appendix 3: Comparison
Chart” for each student Time required: Two lessons Level of conceptual difficulty: Moderate Have the class explain the difference between fresh water
and salt water. If necessary, prompt them with questions,
such as: • What is salt water? Water with salt and other minerals dissolved in it. • What happens if people drink a lot of salt water? They get sick. • Do objects float in both salt and fresh water? Yes, but they float better in salt water. • Do fish live in both salt and fresh water? Yes, but most freshwater fish die in salt water. Salmon
and a few other species are an exception. EXPERIMENT • Divide the class into small groups. Give each group two
containers with approximately 250 ml of water in each, and
approximately 15 ml of salt. • Have the groups prepare a saltwater solution by dissolving
the salt in one container of water. • Give each group two fresh slices of cucumber. Ask the
groups to predict what will happen if they soak the
cucumber in salt water and write their prediction on
“Appendix 3: Comparison Chart”. • Have the groups place one cucumber slice in each container
of water. <
After two hours or more, have the groups compare the
cucumber slices in the two containers. Discuss their
observations. The cucumber in the salt water will be soft and wilted, but
the cucumber in the fresh water will remain crisp. The salt
water draws water out of the cells of the cucumber, making
them less stiff. Suggestions for assessment: Review students’ observation pages and
classroom discussion to ensure that
they can describe how salt water makes
plants wilt. UNIT 7: Salmon Smolts
79 DISCUSSION • Explain that the cucumber slices are like a fish in water. In
fresh water, the fish is normal, but salt water would make
the fish lose its shape as water is drawn from its body. Ask
the class to hypothesize what might happen to a salmon
as it moves from fresh water to salt water. Explain that
salmon smolts drink salt water from the ocean to keep from
shrivelling up. They get rid of the extra salt through their
gills and urine. (See Background Information on page 77.) SUMMATION Have students write or draw their observations and
conclusions on their comparison chart. Illustration: Donald Gunn
• Cucumber slice in fresh water 80 SALMONIDS IN THE CLASSROOM: PRIMARY Cucumber slice in salt water
People
Peopl
INTRODUCTION <
a
nd
an
d
SMOLTS
DISCUSSION <
With younger grades, you may prefer
to do this activity as a chalkboard
demonstration. Materials: • Salmon Life Cycle poster • Copies of “Handout 7.2: People and
Smolts” for each student Time required: One to two lessons Explain that an estuary is an area where a stream or river
enters a larger body of water, such as the ocean. Use the
Salmon Life Cycle poster to discuss with the class why
people like to live near estuaries. They are convenient for river transportation and fishing, they
tend to be flat and good for construction and agriculture,
they are often protected from climate extremes, etc. Have students discuss what happens to smolts and other
wildlife when people build in estuaries. They are crowded out by construction, dyking, dredging, etc.,
and may be affected by pollution from human activities. INVESTIGATION • Give students, in small groups, a copy of “Handout 7.2:
People and Smolts” and discuss it with the class. Have
students work in their group to answer the questions. • When students have completed the handout, discuss the
results. If necessary, prompt them with questions, such as: •
How many smolts could live in the estuary at the
beginning of the activity? 12. •
How many smolts could live in the estuary at the end of
the activity? 3. •
If all the activities listed were done, what would happen
to the smolts? Many would die from lack of food or safe habitat. •
What would happen to other plants and animals that
live in the estuary? Many would die. If smolts cannot live in an estuary, it
is a sign that other plants and animals might also be
unable to live there. •
How can people make sure fewer plants and animals
that live in estuaries die? Try to build inland, protect estuaries, avoid pollution, etc. Level of conceptual difficulty: Moderate Suggestions for assessment: Review the students’ estuary handouts
and discussion to ensure that they can
identify the impact of human activity on
estuaries and smolts. UNIT 7: Salmon Smolts
81 DISCUSSION 82 SALMONIDS IN THE CLASSROOM: PRIMARY <
Discuss with students what happens to an estuary if people
leave natural spaces around estuary construction, replant
vegetation, remove polluting drains, etc. The estuary land can be reclaimed. <
Have students erase some markings from “Handout 7.2:
People and Smolts” to show how land can be reclaimed. <
Discuss with the class how scientists could use information
such as that from the game. To predict the impact of changes on the estuary and prevent
harmful changes. INTRODUCTION • Predator
Game
Have students use the poster or “Handout 7.1: Salmon
Smolts” to list animals that prey on smolts and other
dangers smolts face. Larger fish, birds, snakes, seals, orcas, construction of buildings and roads, pollution.
Option: Have students make large nametags for all of the
predators they identify. These can be used in the simulation. SIMULATION Materials: • Chart paper • Writing supplies • Coloured gym sashes • Option: Gym supplies • Chalkboard • Chalk Time required: One lesson • Divide the class into two teams, with four-fifths of the
students as smolts and one-fifth as various predators (e.g.,
predatory fish, birds). Give each group a different colour of
sash. • Label one side of a gym or open area “Home Stream” and
the other side “Ocean”. Label the area in between “Estuary”. • Have the predators take various places in the estuary, in the
middle of the gym floor. Explain that predators can catch
smolts by tagging them as they cross the floor from the
home stream to the ocean. • Have the smolts try to move from the home stream to
the ocean without being caught by the predators. Once
students have been tagged, have them move to the outside
of the play area so as not to become a danger to the other
students. Have students count and record the number that
make it safely to the ocean. Have students change roles
and play the game again. Have students vary the number of
players on each team and record the number of smolts who
make it to the ocean. • With the class, use the game counts to graph the results.
Have older students calculate the rate of smolt survival
(e.g., one out of five). Level of conceptual difficulty: Simple Suggestions for assessment: Monitor student discussions and review
their reflections on the predator game
to ensure that they can identify how
predators reduce the number of smolts. Stream Salmon Smolts Estuary Predators Sea Maturing Salmon Predators Illustration: Donald Gunn UNIT 7: Salmon Smolts
83 • Extension activity: Use gym equipment to represent other
hazards, such as dams, logs or polluted water. Play the game
again and have students compare the outcome. Have smolts
move together in a large school and compare the outcome,
or have students create safe spaces and protected areas in
the estuary where smolts can hide from predators. DISCUSSION • Have students discuss how the game compares with
the hazards smolts face as they travel to the ocean. If
necessary, prompt them with questions, such as: •
What are the similarities between the game and a real
smolt’s trip to the ocean? It is a hazardous trip and many smolts do not survive. •
What are the differences between the game and a real
smolt’s trip to the ocean? The real route is much longer. Smolts can hide under the
water. • What happens when the number of predators increases? Fewer smolts survive. •
What happens when dams or other obstacles block the
way? Fewer smolts survive. • What does the game show about the smolt’s trip? Predators and obstacles prevent many smolts from
reaching the ocean. SUMMATION 84
SALMONIDS IN THE CLASSROOM: PRIMARY <
Have students write a reflective sentence or paragraph about
the predator game. Use the sentence stem, “When playing the game, I thought….” <
Have students draw and label on the chalkboard the hazards
a smolt faces on its trip to the ocean. Pollution, obstacles en route; adaptation to salt water; loss of
estuary habitat; predators in the estuary. • Explain that many smolts do not survive the trip to the
ocean, but that the estuary is a rich environment for smolts
to grow and prepare for life in the open ocean. Smolt Predators
Otter
Belted Kingfisher
Red-breasted Merganser Great Blue Heron
Illustration: Donald Gunn
Orca
Sculpin
Seal
UNIT 7: Salmon Smolts
85